Rock drill



| A. B. HUTTON Dec. 7, 1943.-

ROCK DRILL Filed Ag zril 9, 1945 M i m Patented Dec. 7, 1943 ROCK DRILL Lionel Alfred Bennett Hutton, Ottawa, Ontario, Canada Application April 9, 1943, Serial No. 482,365 In Canada April 3, 1943 13 Claims.

This invention relates to rock drills of the detachable bit type.

The use of detachable bits for rock drills has now become quite widespread in the mining industry due to many obvious advantages thereof. It is well recognized, however, that there is room for improvement in many of meansheretofore proposed for attaching or locking the bit to the shank of the drill. The common dovetail has been frequently employed as such locking means. One of the disadvantages of the dovetail is that, unless tolerances are very accurate and close, play develops between the bit and shank and an appreciable loss of energy occurs. If, however, tolerances are very close, it is diflicult to insert and remove the bit from the shank. If tolerances are such as to permit ease of'insertion or withdrawal of the bit from the shank, there is a tendency of the bit to slide sidewise when the drill is operating in broken or soft rock or when it enters a fissure.

The object of the present invention is to provide a rock drill construction in which the detachable bit may be readily attached and removed from the shank; in which the bit is positively held in position during the normal rotating operation of the drill; in which, despite wear in use, there is maintained throughout the useful life of the bit a substantial area of intimate surface contact between the bit and shank to reduce greatly loss of energy in operation and to prolong the life of the shank by reducing wear due to play between the shank and bit; and in which the means for locking the bit in position on the shank at the same time insures the intimacy of contact between the complementary bearing surfaces of the bit and shank.

A primary feature of the invention resides in the provision on the end of either of the members of a rock drill, of a curved tongue having a somewhat enlarged head portion extending at right angles to the axis of the member and a complementary recess on the other member to receive the tongue. These complementary curved surfaces insure, during normal rotating operation of the drill, that the bit and shank remain locked in intimate contact over their complementary bearing surfaces. This avoids loss of impact energy used in operating the drill, and, at the same time, prevents unintentional displacement or loss of the bit in a drill hole. Despite thi intimate contact in the operating position the bit is easily removed from the shank by slight counter-rotation.

Other objects and advantages of the invention will be apparent from the following description with particular reference to the accompanying drawing, in which Figure 1 is a plan view of a bit constructed in accordance with the invention.

Figure 2 is a partial sectional elevation of a drill including the bit of Figure 1.

Figure 3 is a plan view of a modified form of it Figure 4 is a partial sectional elevation of a drill including the bit of Figure 3.

Figure 5 is a plan view of another form of bit in accordance with the invention.

Figure 6 is a partial sectional elevation of a drill embodying the bit of Figure 5.

Figure 7 is a plan view of another modified form of bit.

Figure 8 is a partial sectional elevation of a drill embodying the bit of Figure 7.

Figure 9 is a plan view of another modified form of bit.

Figures 10 and 11 are partial sectional elevations of a drill including the bit of Figure 9.

Figure 12 is a plan view of a modified form of bit.

Figures 13 and 14 are partial sectional elevations of drills embodying additional modifications, and

Figure 15 is a plan view illustrating the mode of insertion of the bit into the shank.

Referring to Figures 1 and 2, the bit I has a transversely extending curved tongue 2 in the shape of a dovetail on the upper end thereof. The tongue has arcuate parallel sides, as shown, and extends from one edge of the bit to a point adjacent but spaced from the opposite edge. The shank 3 has a complementary curved recess 4 in its lower end to receive the tongue. It will be observed that such a recess is open at one end for entrance of the tongue thereinto and closed at the other end to provide a stop for the tongue. The recess is preferably somewhat deeper than the tongue to provide a clearance, as indicated at 5, between the top of the tongue and the bottom of the recess. Thus, the major portions 5 and I of the end surfaces of the bit and shank, respectively, have positive and intimate contact with each other to eliminate substantial loss of energy during operation of the drill.

Referring to Figures 3 and 4, the bit 8 has a curved dovetail-shaped recess 9 transversely ex-- thereof constitutes the major bearing portion of the end surface of the bit. The sides of the recess are in the form of arcs the geometrical center of each of which lies on a line passing through the center of the bit. A stop H is provided at one end of the recess. The shank l2 has a complementary tongue l3 on the end thereof and a recess i to receive the stop II. In

' this instance clearance, as indicated at 15, is

preferably provided on the opposing portions 16, I6 of the bit and ll, ll of the shank to ensure positive bearing contact of the major bit surface with the complementary surface of the shank.

Referring to Figures 5 and 6, a bit I8 has a" curved dovetail-shaped tongue I9 transversely extending from edge to edge thereof. Thetongue becomes progressively and gradually narrower from one end to the other. The shank has a complementary recess 21 therein. The wedgeshaped character of the tongue and recess constitutes a positioning stop for the bit but obviously should not be such as to develop undue lateral strain in the shank. The clearance indicated at 22 between the bottom of the recess and the top of the tongue ensures intimate contact between the bearing surfaces of the bit and shank thus reducing loss of energy and wear.

Referring to Figures 7 and 8, a bit 23 has a curved dovetail-shaped recess 24 transversely extending from edge to edge thereof. The recess, as in the form shown in Figures 3 and 4, has a broad bearing surface 25' constituting the major portion of the end surface of the bit. The recess is somewhat wider at one end than. the other; The shank 26 has a complementary curved tongue 2i. As in the form illustrated in Figures 3 and l, the wedge-shaped character of the tongue and recess constitutes a positioning stop for the bit. The clearance indicated at 28 between the minor opposed surfaces of the bit and the shank ensures the intimate bearing contact.

Referring to Figures 9, l0 and 11, a bit 29 has a curved tongue 3i! transversely extending from edge to edge thereof. The tongue has arcuate parallel sides and an enlarged head portion 3|. The shank 32 has a complementary arcuate recess 33. In order to ensure positive locking and intimate bearing contact between bit and shank, the major abutting surfaces 34 of the bit and 35 of the shank are complementarily transversely inclined, as shown in- Figure 11.

Figure 12 illustrates a bit of the type shown in Figures '7 and 8, but wherein an edge portion of the bit, opposite to the recess, is cut away as indicated at 38 to provide conservation of metal. The remaining edge portions 31 of the recess are believed to provide suflicient support for the complementary tongue of the shank.

The feature illustrated in Figures 13 and 14 consists in providing complementarily inclined abutting surfaces on the major end portions of the bit and shank, such surfaces extending from substantially the'same plane and coinciding with the outer periphery of the surfaces. 13, the bit 38 has a tongue 39 for insertion in the slot 40 of shank 4| and major contacting sur--- faces 42 of the bit and 43 of the shank areupwardly inclined in straight contour from the outer periphery of the surfaces. In Figure 14, the bit 44 has a recess-45-to receive the tongue 46 of the shank ll, andmajor contacting surfaces 48 on the'end of the tongue and 49 atthe bottom of the recess are upwardly inclined in curved contour from the outer periphery of the surfaces. It will be apparent that a curved. contour may be substituted for the straight contour In Figure l0 and 11.

of surfaces 42 and A3 in Figure 13 and that a straight contour may be substituted for the curved contour of surfaces 48 and id in Figure 14. Moreover, such surfaces may be downwardly, instead of upwardly, inclined as shown. The inclination of these surfaces serves to counteract any tendency of splitting the member in which the recess is formed.

As shown in Figure 15, which illustrates the mode of insertion of the bit i 8 into the shank 20, such insertion is readily and conveniently accomplished in all modifications of the invention; It will be observed that, after positioning of the bit on the shank, normal operating rotation of the drill tends to maintain these members in positive and intimate locking contact, there being no tendency or possibility of dislodgment' of the bit.

The usual Water hole 53 may be provided in all forms.

. The substantial area of bearing contact between bit and shank is suflicient for transmission of the impact force of the drill without injury to either member due to the intimate and uniform contact which is provided throughout such area. Moreover, as wear of the contacting surfaces occurs in the forms shown in Figures 5, '7 and'9, such wear is automatically taken up by slight rotativemovement of the shank with respect to the bit whereby the intimate contact is maintained throughout the life of the bit.

In the forms shown in Figures 1 and 3 it will be apparent that the'major bearing surfaces may be transversely inclined as shown in Figures 9, This, would insure the maintenance of intimate contact between the bearing surfaces, automatically take up wear, and eliminate the need of the stops shown in Figures 1 and 3.

It will be apparent that various changes in details of the illustrated forms and various other modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It is contemplated that the curved sides of the tongues and recesses described may be truly arcuate or of any other curved formation which will provide complementaryinterlocking surfaces.

Iclaim:

I. In a rock drill having bit and shank members, atongue on the end of one of the members, at least one end of the tongue coinciding with the edge of said end' of the member, the longitudinal contour of one side wall of the tongue being concave and the longitudinal contour of the other side wall being convex, said tongue having an enlarged head extending at right angles to the longitudinal axis of the member, the other member having a complementary recess to receive said tongue.

2. In a rock drill having bit and shank members mounted in end to end relation, means securing, said members together comprising a tongue on the end of one member, at least one end of the tongue coinciding with the edge of said end of the member, the longitudinal contour of one side wall of the tongue being concave and the longitudinal contour of the other side wall being convex, said tongue having an enlarged head extending at right, angles to the longitudinal. axis of the member, the other member having a complementary recess receiving said tongue, said members having opposed end surfaces in two planes, the surfaces in one plane of. greater area being in contacting relation and the surfaces in the other plane of less area being in spaced relation.

3. In a rock drill having a bit and shank mounted in end to end relation, means securing said bit and shank together comprising a dovetail tongue on the end of the bit, at least one end of the tongue coinciding with the edge of said end of the bit, the longitudinal contour of one side wall of the tongue being concave and the longitudinal contour of the other side wall being convex, said tongue extending at right angles to the longitudinal axis of the bit, the shank having a complementary dovetail recess receiving said tongue, the top surface of the tongue being of substantially less area than that of the ad jacent end surface of the bit, said top surface being in spaced relation to the bottom of said recess when said adjacent end surface is in contact with the opposed end surface of the shank.

4. In a rock drill having a bit and a shank mounted in end to end relation, means securing said bit and shank together comprising a dovetail tongue on the end of the shank, said tongue having side walls extending at right angles to the longitudinal axis of the shank, the longitudinal contour of one of said side walls being concave and the longitudinal contour of the other side wall being convex, the bit having a complementary dovetail recess receiving the tongue, the

top surface of the tongue being of substantially greater area than the adjacent end surface of the shank, said adjacent end surface being in spaced relation to the opposed surface of the bit when said top surface is in contact with the bottom surface of said recess.

5. In a rock drill having bit and shank members mounted in end to end relation, means securing said members together comprising a curved tongue on the end of one member, said tongue having an enlarged head extending at right angles to the longitudinal axis of the member, the other member having a complementary recess to receive said tongue, the opposed end surfaces of said members adjacent the tongue and recess being transversely inclined.

6. A rock drill bit comprising a body member, a tongue on one end of said member, said tongue having at least one end coinciding with the edge of said end of the member, the longitudinal contour of one side wall of the tongue being concave and the longitudinal contour of the other side wall being convex, said tongue also having an en-,

8. A rock drill bit comprising a body member,

said member having a dovetail-shaped recess in its end extending transversely from edge to edge thereof, the sides of said recess being curved.

9. A rock drill bit as defined in claim 8, wherein the bottom of said recess constitutes the major surface area of said end of the bit.

10. A rock drill bit as defined in claim 8, wherein at least one side of said recess has a cut-away portion.

11. A rock drill bit as defined in claim 6, wherein the end of said member adjacent said tongue is transversely inclined.

12. A rock drill bit comprising a body member and a dovetail tongue on one end of said member, said tongue having a curved contour in a plane at right angles to the longitudinal axis of the body member.

13. In a rock drill bit having an end adapted for attachment to a shank, said end having a recess extending transversely thereacross, one side wall of said recess having a concave longitudinal contour and the other side wall of the recess having a convex longitudinal contour, said recess being of greater width at one end than at the other, and the bottom of the recess having a uniformly greater width than that of the top thereof.

LIONEL ALFRED BENNETT HUTTON. 

